In the semiconductor industry, cleanrooms are used for the production of electronically sensitive components such as microchips. This article explains how cleanrooms work in semiconductor production and why ESD protection must also be taken into account.

Classification of cleanrooms

Cleanrooms – also known as ultra-clean rooms – are areas in which the number of particles in the air is kept as low as possible in order to prevent contamination of the products being manufactured. Cleanrooms are extremely important in the semiconductor industry in particular, as the electronic components that are manufactured there are very sensitive and must therefore be protected from contamination.

Cleanrooms are divided into classes depending on how many particles are permitted per cubic meter of air. There are various systems for defining these classes, including the GMP and ISO systems, whereby the GMP classification divides cleanrooms into 4 cleanroom classes and the ISO classification into 9 cleanroom classes.

Functionality of cleanrooms in the semiconductor industry

In a clean room, the air that enters the room is first purified by ultra-fine filters. The purified air is fed in via the ceiling and discharged via holes in the floor. A slight overpressure in the cleanroom is also intended to prevent particles from outside entering the cleanroom.

In the production of wafers in the semiconductor industry, special transport containers known as FOUPs are used to prevent the wafers from being exposed to cleanroom air when they are transported from one machine to another. FOUP is the abbreviation for Front Opening Unified Pod. By sealing off the FOUP units, conditions can prevail in them that meet the requirements for a far lower cleanroom class than outside the units in the cleanroom itself. It is therefore possible to meet the requirements for cleanroom class ISO 1 or ISO 2 in the FOUPs, while only the requirements for ISO 5 are met in the cleanroom around them. The advantage of this separation of the protection level is that a lot of costs can be saved, as only small areas have to meet the requirements of the highest cleanroom classes. Other measures to keep the cleanroom free of particles include air showers in front of the cleanroom entrances, which can be used to blow particles away from people who want to enter the cleanroom. The people working in the cleanroom usually wear a cleanroom suit (cleanroom overall) and other cleanroom clothing such as cleanroom shoes to reduce particles. Cleanroom gloves are also used.

ESD protection is just as important

In addition to protection against particles, measures must also be taken against uncontrolled electrostatic discharges when manufacturing semiconductors. This is because even very small discharges can cause major damage to the semiconductor components.

The problem here is particularly latent damage, which is also referred to as “walking wounded” or “latent failure”. In most cases, it is not even noticeable during the final inspection if semiconductor components have been damaged by electrostatic discharge, as the damage does not initially affect the function of the component. However, once the components have been installed in the end devices and these are in use, the hidden damage will sooner or later lead to malfunctions or even failures. The cost of repairing the damage to the installed components is then many times higher than if the damaged component had already been sorted out during the final inspection. However, since – as already mentioned – these damaged components are not usually detected during the final inspection, it is important to avoid the damage itself, i.e. electrostatic discharge.

The greatest risk of uncontrolled electrostatic discharges comes from people, for example as a result of charges caused by friction. For this reason, care should be taken in semiconductor production to ensure that employees wear ESD clothing and work in special ESD protection zones.

Advice on cleanrooms and ESD in the semiconductor industry

The abovo online store team has experience in the ESD and cleanroom sectors. So let our experts advise you on which products meet both ESD and cleanroom requirements. Abovo is your ideal partner if you work in the semiconductor industry, for example.

The best way to contact the experts at abovo is by telephone or e-mail. Take the opportunity now to get non-binding advice from us or to clarify any unanswered questions:

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